This invention relates to a portable writing board mountable for use on a steering wheel of a vehicle and also useful in other environments apart from a steering wheel. The most preferred embodiments have a special feature to make the writing board entirely stable for writing use when rested upon any flat surface. The invention also relates to the writing board in various combinations with other structures such as a shelf, a clip, and also the steering wheel of a vehicle.
All heretofore known portable writing boards for the steering wheels of vehicles have suffered from instability and a tendency to scratch when one has attempted use of them as a writing board on a substantially flat surface apart from a steering wheel. The under surface of those heretofore known has frequently been equipped with spaced and centered projecting elements useful in the mounting of the writing board to a vehicle steering wheel but highly objectionable when employing the board in any other environment.
Additionally, the mounting techniques heretofore employed for holding the writing board on a steering wheel have been relatively complex with none approaching the utter simplicity of the unitary collar structure of this invention and its performance features Insofar as is known, no one has ever heretofore provided a continuous collar structure of gripping or pinching character for steering wheel mounting. Further, insofar as known, no one has provided a collar structure of such character and additionally having features or elements of sufficient rigidity and design for stable support of the writing board on a flat surface.
An important aspect of the most preferred embodiments of my invention is the ability of a single size writing board to accommodate a variety of vehicle steering wheel diameters and rim thicknesses. The diameter of vehicle steering wheels varies considerably. The thickness of the steering wheel rim generally increases as the diameter decreases, and the rim thickness decreases as the diameter increases. The prior art writing boards generally must be tailored to fit specific different sizes of steering wheels, and any one single form of manufacture for them is not centerable on all sizes of steering wheels. My most preferred writing board, however, centers well on a variety of steering wheels because of the placement of different rim thicknesses within the tapering recess of the compound collar of the board. A larger diameter wheel with a small rim thickness fits deep into the recess in a pinched manner. Therefore, the lower edge of the platform member will usually be located close to the diametrically opposite portion of the steering wheel rim, causing the platform member to be relatively centered over a larger diameter steering wheel. However, a smaller diameter wheel with a large rim wheel with a large rim thickness does not fit very deeply into the tapering recess, but still is pinched by it, thus causing the upper curved edge of the platform member to extend out from the steering wheel rim, with the result that the overall extent of the platform member is relatively centered over a smaller diameter steering wheel.